some good modern rts games?

I just got a gaming pc and I loved halo wars on xbox and I heard these kind of games are quite popular on pc so any kind of strategy game as long as it's real time I hate turn based! apart from xcom that game was fucking awesome....

Starcraft 2 + Expansion is one of my favorites even though I suck at the multiplayer. The story is great though. Also Company of Heroes seems to be solid and liked by many.

Since you seem to like the Sci-Fi with Halo Wars I would go with Starcraft 2 and the expansion.

Dawn of War is another good option

Agreed as @Arthas045 mentioned SC2 + HoS expansion, and of course the upcoming new expansion